Some years after his escape from captivity Caesar heads a vast colony of apes and chimps living a self-sufficient life in the woods outside San Francisco. In the city itself a depleted group of Simian Flu survivors struggle to exist, their best hope being to revitalise a hydro-electric dam which will restore their power. However to reach it they must pass through Caesar's domain. Group leader Malcolm and Caesar have a mutual respect which allows the restoration to take place but Caesar's embittered lieutenant Koba, a victim of animal experimentation, has no such faith in humans and usurps Caesar, leading a full-scale attack on the city, most of whose inhabitants regard the apes as savages and a fierce battle takes place. It is down to Caesar and Malcolm to join the voices of reason together to re-establish a peace which will benefit both camps.